To hedge my bets financially, I've purchased an HD DVD player, reduced my disc purchases, and subscribed to NetFlix to keep up with the latest releases.
I think that Bob's hit on perhaps the best advise at this stage in the format war -
neither format has earned the classification of a successful format or a sure bet yet, and I'm not sure when (or if) either will reach that sort of critical mass in the marketplace. Until then, investing in hardware or software (especially software) needs to be done with the awareness of that.